1. Field of the Invention
The present invention relates to an outboard motor. More specifically, the present invention relates to an outboard motor having a system for minimizing the possibility that water will impinge on an internal combustion engine of the outboard motor and/or enter the engine air intake system.
2. Description of the Related Art
Conventionally, an outboard motor comprises an internal combustion engine enclosed in an engine compartment defined by a cowling comprising a top cowling and a bottom cowling. An intake air duct is formed through the cowling for supplying air to the engine. The cowling air duct is generally provided with a water-separating structure for preventing the entrance of water from outside the cowling. The air duct preferably has a cross sectional area large enough to secure an adequate amount of intake air. Therefore, it may be difficult to keep water from entering and flowing through the intake duct.
Water entering the cowling typically contacts the top face of a flywheel magneto cover. From the flywheel cover, water flows or drips to the bottom of the cowling. Possibly, water may drip onto the engine from the flywheel equipment cover, or water accumulated in the bottom of the cowling may scatter onto the engine or auxiliary due to vibration or trimming, turning tilting motion of the outboard motor. Also, there is a possibility that water is ingested by the engine via its air intake system.
In one known technique, water accumulated in the bottom of the cowling is drained by means of a check valve. This technique does not work until a sufficient amount of water is accumulated to push open the check valve. In addition, it may take a long time to drain the water completely.
Technology also exists to prevent water that enters a cowling from dripping directly on an engine. However, since the water accumulates in the bottom cowling before it is drained, it can scatter and splash onto the engine prior to being drained due to vibrations and/or motion of the motor due to wave action.
In other art, a water drain outlet on the top cowling faces rearward and has a cover. This structure is especially susceptible to water intrusion, especially is a large wave contacts the outboard motor. In addition, there is a chance that water will flow back from the drain outlet into the outboard motor.
Large outboard motors with high power output typically require large quantities of intake air for engine operation. Thus, a cross-section of an intake air duct is typically relatively large for such motors in order to assure a sufficient amount of air is provided to the engine. As such, water intrusion prevention techniques are typically less effective for such motors, and problems in connection with accumulation of water in the bottom of cowlings are particularly relevant in large, high power outboard motors.